Electromagnetic relay

ABSTRACT

The inventive relay has a base body in the form of a coil body ( 1 ), the base body supporting a core ( 16 ), a yoke ( 20 ), an armature ( 22 ) and a contact spring ( 23 ) which is connected to the armature. Fixed contact supports ( 34 ) and a contact spring connection pin ( 5 ) which consist of semi-finished wire with a preferably rectangular or square cross-section are embedded in a flange ( 12 ) of the coil body ( 1 ). The inventive electromagnetic relay is therefore very simple to produce. There is no wasted material, no punching tools are needed for the contact connection parts and since no particles of plastic are abraded by insertion, there is no risk of this impairing the quality of the relay.

BACKGROUND OF THE INVENTION

The invention relates to an electromagnetic relay with the followingfeatures:

a coil body forms a coil tube with two flanges and carries a winding onthe coil tube;

a first of the two flanges forms a switch space with a base sideparallel to the coil axis;

within the coil tube there is arranged an axial core which forms a poleface toward the switch space and is connected to an L-shaped yoke in theregion of the second flange;

with its free end, the yoke forms, in the region of the switch space, abearing edge, perpendicular to the base side, for a plate-shapedarmature which forms a working air gap with the pole face of the core;

at least one, fixed contact support carrying a first fixed contact issecured in the coil body in the vicinity of the moving end of thearmature and

a contact spring formed from flat strip material is connected to thearmature, carries a moving contact at one free end in the region of themoving end of the armature and is connected to a contact springconnecting pin of the relay via a connecting portion.

A relay constructed in this way is known, for example, from U.S. Pat.No. 4,596,972. The contact spring there surrounds the armature mountingin the form of an arc and is fastened to the yoke by its connectingportion, the yoke in turn forming a downwardly shaped connecting pin.With a relay of this type, in which the load current is guided via theyoke, the current path in the relay to the connection is relativelylong; the ferromagnetic yoke material also has limited conductivity.This is undesirable for the switching capacity of high currents if theconnecting pin with its relatively small cross-section is also producedfrom the same material. A connecting pin shaped on the yoke alsonecessitates additional expenditure, if the relay housing is to besealed.

In the case of similarly constructed relays which are designed for highload currents, it is known to guide the load current from a connectingpin fastened in a base via a flexible copper wire directly to thecontact spring and to the contact piece fastened thereon (DE 34 28 595C2). In this way, the yoke does not have to carry the load current.However, the use of the flexible wire necessitates additionalexpenditure for material and assembly.

With this known relay, the fixed contact supports and optionally alsothe contact spring connecting pin are produced as respective punchedparts and are assembled by plugging them into preshaped ducts andapertures in the coil body or a base and then fixed by a notchingprocess or inherent pressing. This design has the drawback that theparts do not fit in the plastic part in an interlocking manner forreasons of tolerance or that particles are abraded during assembly owingto overlapping of parts. These particles can subsequently lead toproblems in the relay, for example on the contacts, in the armaturebearing or in the working air gap. High expenditure then has to beincurred during production, to eliminate the resultant particles byblowing or extraction devices.

It is known with other relays to punch individual parts such as contactsupports from sheet metal and to extrusion-coat them either individuallyor linked in strips in a mould. This method of production has thedrawback that the parts have to be inserted into the injection mould;strip production also entails high consumption of material. Highexpenditure is required in both cases for adapting the injection mouldto the punching tools, in order to allow the mould to be sealed well inthe region of the punching burrs.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to create a relay of the typementioned at the outset with a simple design, which can also be producedeasily with few parts. In particular, the construction should allow theuse of particularly desirable semi-finished materials and waste-freeproduction processes which are particularly economical with materials,so that the relay can be produced particularly economically but stillwith high quality.

According to the invention, this object is achieved with a relay of thetype mentioned at the outset in that the contact spring connecting pinand the at least one fixed contact support consist of drawn or rolledwire and are embedded in the coil body.

The use according to the invention of wire connecting elements for theload circuit connections allows particularly inexpensive production ofthe relay, which is economical in material. As the semi-finished wire isinserted into the injection mould directly from the supply roll and isembedded there, punching and bending tools are not required. The coilconnections used in the normal manner are also preferablyextrusion-coated in the mould in the same manner. The wire can beseparated either before being extrusion-coated or after beingextrusion-coated, directly by the injection moulding tool, without theformation of waste. The sealing of the injection mould isunproblematical owing to the use of drawn or rolled wires with a simple,preferably round or rectangular profile, as punching burrs or the likedo not have to be allowed for. As the relay does not have any plugged-inpunched parts, no plastic particles which could damage the contactsurfaces or pole faces are shaved off during assembly.

In the simplest configuration, the relay has only one fixed contactwhich interacts with the contact spring as a make or break contact andis accordingly arranged on one or other side of the spring end with themoving contact. Similarly, however, a make-and-break contact can also beproduced, in which case a second fixed contact support with a secondfixed contact is secured in the same coil body flange opposite thefirst.

In a preferred embodiment of the invention, the contact springconnecting pin is also embedded in the first coil flange, in other wordsin the region of the switch space, and the connecting portion of thecontact spring is fastened directly on a portion of the connecting pinextending parallel to the bearing edge of the yoke. The armature lieswith its bearing end between the yoke end and the connecting pin in thiscase while the connecting portion of the contact spring is guided pastthe bearing end of the armature to the connecting pin and is fastened,preferably welded or hard soldered, thereon.

In an advantageous configuration, the contact spring connecting pin,like the fixed contact support, consists of square wire in each case. Inthis case, the contact springs on the one hand and the fixed contacts onthe other hand can be welded or soldered with a large transitional areato the support. The fixed contacts themselves are preferably alsoseparated from a semi-finished contact strip as portions, so no waste isproduced here either.

The core arranged in the coil tube preferably possesses a pole platewith a pole face which is enlarged eccentrically toward the armaturemounting. Therefore, even with small relay dimensions, on the one handan adequate insulating distance from the fixed contacts and on the otherhand a sufficiently large pole face can be produced. In an advantageousconfiguration, the core can be embedded in the coil body duringproduction of the coil body, making a subsequent plug-in processunnecessary. In this case, the core can have a round or also arectangular cross-section. However, it is also possible to plug a round(or rectangular) core into a through-orifice of the coil member at thelater stage. In this case, it is advantageous to provide, on the coresurface in the vicinity of the pole plate, embossed studs which form aninterlocking fit during subsequent relaxation of the thermoplastic corebody material and which therefore fix the core pole face and the bearingedge of the yoke reciprocally in position.

In an advantageous configuration of the invention, the contact spring isalso fastened on the yoke by a fastening portion surrounding thearmature mounting at an angle and a connecting portion folded over thefastening portion is guided to the connecting pin and connected to it.This ensures that a large spring cross-section is available for guidingthe load current to the connecting pin in a relay for high loadcurrents.

As a result of the embedding of all load connections in the region ofone coil flange, the connections are already guided tightly downwardlythrough the base of the switch space. Therefore, a cap placed onto thecoil body merely has to be sealed along the external contour of the coilflange. The same applies to the opposing second flange, where aninjection moulded coil connecting pin is also already embedded tightly.Therefore, there remains only the space beneath the coil winding caneasily be closed by a plate and sealed along its edges.

The embodiment will be described in more detail hereinafter byembodiments with reference to the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a relay designed according to theinvention (without housing cap),

FIG. 2 shows the relay from FIG. 1 in the partially assembled state(with housing),

FIG. 3 is a horizontal longitudinal section through the finallyassembled relay from FIG. 1,

FIG. 4 shows a plug-in core for the relay according to FIG. 2,

FIG. 5 is a vertical longitudinal section through the relay from FIG. 1with a core according to FIG. 4,

FIG. 6 shows a modified housing cap with a flexibly moulded base plate,

FIG. 7 shows a relay in a view corresponding to FIG. 1 with a modifiedcontact spring, and

FIG. 8 shows the arrangement of two relays according to FIG. 1 with ahousing for forming a double relay.

DETAILED DESCRIPTION OF THE INVENTION

The relay shown in FIGS. 1 to 5 possesses, as supporting part, a coilbody 1 with a coil tube 11, a first flange 12 and a second flange 13.The first flange 12 forms a projection in which there is formed a switchspace 14 which is closed at the bottom by a base 15 and thereforedefines the connecting side of the relay. A winding 2 is arranged on thecoil tube 11.

Two fixed contact supports 3 and 4 and a contact spring connecting pin 5are embedded in the projection of the first flange 12 by extrusioncoating and are designed as a semi-finished product made of highlyconductive material, for example copper, as a square wire. Instead ofthe illustrated wire with a square cross-section, a wire with arectangular or round cross-section could also be used. The two fixedcontact supports are provided with a respective fixed contact on themutually facing surfaces, namely a first fixed contact 6 which acts as amake counter contact and with a second fixed contact 7 which acts as abreak counter contact. These contacts are cut in each case as contactpieces from a strip of semi-finished contact material and are welded or(preferably) hard soldered on the fixed contact support 3 and 4.

Two further wires preferably with a smaller cross-section are diagonallyoffset as coil connecting pins 9 and 10 in the second or in the firstflange and are embedded in the same manner as the load connections.These coil connecting pins are preferably designed with a squarecross-section so that the initial turns at the ends of the winding arebetter fixed prior to being connected in terms of material. Thisconnection is preferably produced by TIG welding or TIG soldering,during which a flux-free and therefore particle-free connection isproduced.

The coil tube 11 contains a round or rectangular soft magnetic core 16with an integrally shaped pole plate 17 from the contour of which asegment is separated on one side along the line 18. A large pole face isthus obtained, in particular on the side directed toward the armaturemounting whereas a sufficiently large insulating distance from the fixedcontact support 3 is ensured on the opposite side. The core end 19opposing the pole plate 17 projects from the coil tube and is connectedto one arm 20 a of an L-shaped yoke 20. The second arm 20 b of theL-shaped yoke 20 extends laterally parallel to the coil axis and forms abearing edge 21 for an armature 22 at its end.

With the hollowing of the coil body 1, the core 16 can be embeddedtherein, in other words in the coil tube 11, so that subsequent pluggingin is unnecessary (see FIG. 3). In this case, the core end 19 projectingbeyond the coil body serves to centre the core in the injection mould.

To prevent armature erosion (over-travel) for the service life of a makecontact in the case of an extrusion-coated core, the armature has a freeembossment 22 b in the region below the movable contact spring end, sothat an air gap 28 is created between the contact spring 23 and thearmature 22. A set bending point is also predetermined by lateralconstrictions 22 c. It allows the over-travel to be increased if thearmature is easily kinked by the force of the coil axis.

However, it is also possible to plug the core into the coil tube at alater stage according to FIG. 2. In this case, it is advantageous toemboss studs 16 a on the periphery of the cylindrical (or rectangular)core in the vicinity of the pole plate 17, as shown in FIGS. 4 and 5.These projecting studs 16 a are oversized in the region of the coilflange 12 in the assembled state and produce an interlocking fit duringsubsequent relaxation of the thermoplastic material; the core pole faceis therefore fixed in position on the pole plate 17 and the bearing edge21 of the yoke in the coil body and therefore in relation to the fixedcontact supports embedded in the coil body. Tolerances in the two partsare eliminated and an optimum force of magnetic attraction achieved forthe armature since the core and the yoke are connected, for example by anotched connection, in the region of the coil flange 13 in such a waythat the pole face of the pole plate 17 and the yoke bearing edge 21 arealigned with one another. Tolerance compensation and over-traveladjustment are effected in such a way that the notched yoke/core unit isinserted axially in the coil tube until the over-travel of the armatureattains its set value. The reciprocal arrangement of the optimallyaligned faces in the working and armature mounting air gap do notchange; only the magnet system is adapted to the position of the contactassembly. Relaxation of the thermoplastic coil body material can beaccelerated by the additional effect of forces F on opposing sides ofthe coil flange 12 (see FIG. 5) perpendicularly to the coil axis, sothat the fixing of the core in the region of the flange 12 is ensuredafter adjustment.

A contact spring 23 is connected to the armature 22 by a riveted joint24 carrying, at its end 23 a projecting beyond the armature, a movablecontact 25 which interacts with the two fixed contacts 6 and 7 as acentral contact. As in the embodiment illustrated, it can be designed asa riveted contact or can also be formed by two contact pieces which arewelded or soldered against one another and separated by a strip of highgrade metal. In the region of the armature mounting, the contact spring23 possesses a fastening portion 23 b which is bent in the form of acurl or a loop over the mounted end of the armature and is fastened flaton the yoke arm 20 b with riveted studs 26 (or welded spots). Thisfastening portion 23 b of the contact spring produces the armaturerestoring force owing to its bias. The contact spring 23 also possessesa connecting portion 23 c which extends beyond the fastening portion 23b, is folded round 180° over the fastening portion 23 b and is fastenedby its end on the connecting pin 5 by welding or hard soldering. Thisconnecting portion of the spring is used only for carrying current anddoes not affect the restoring force of the armature. It is provided withapertures 27 in the region of the rivet studs 26 (or welded spot), so itis not co-riveted. To prevent impacts, the armature 22 possesses asecuring nose 22 a which penetrates into a rectangular hole 23 d punchedin the fastening portion 23 b and secures the armature axially relativeto the coil.

The open printed-circuit board relay according to FIG. 1 describedhitherto can be provided with a protective cap 29 according to FIG. 2. Abase plate 30 which covers the coil winding space at the bottom canadditionally be inserted in the region of the base between the twoflanges 12 and 13. The gaps between the cap 29, the base plate 30 andthe coil body 1 can then be sealed by a casting compound. The base plate30 covering only the coil space does not cause abrasion of particles asthe wire-shaped connections, namely the fixed contact supports 3 and 4,the contact spring connecting pin 5 and the coil connecting pins 9 and10 are embedded in the flanges and do not require apertures in the baseplate. The base plate 30 can also be connected integrally to the cap 29by a film hinge 31 according to FIG. 6. In this case, it is pivoted overthe coil space after assembly of the cap and sealed.

FIG. 7 shows a relay similar to that in FIG. 1 but with a modifiedcontact spring 33. In comparison to the previously described contactspring 23, with which a large conductor cross-section is provided forhigh currents by means of the folded connecting portion 23 c, thesimplified form of the contact spring 33 can be used for lower currentloads. In this case, the contact spring 33 possesses a bearing portion 3b which is bent over the armature mounting while a connecting portion 33c also used for fastening purposes is cut from the central region of thespring and is guided parallel to the yoke surface directly to thecontact spring connecting pin 5. The welded or soldered spot 34 is usedboth for the fastening and for the electrical connection of the contactspring. Individual fastening on the yoke is unnecessary. The remainingspring arms 33 d and 33 e produce the restoring force of the armaturecontact spring unit. Otherwise, this relay according to FIG. 7 isconstructed in exactly the same way as the previously described relay.

The relay can also be provided as a double relay with a common housing.As shown in FIG. 8, in this case, two individual relays with arespective coil body 1 according to FIG. 1 are arranged side by sidewith their coil axes in parallel and are provided with a common cap 35and a common base plate 36. The gaps between the cap and the base plateon the one hand and the coil bodies 1 on the other hand are sealed withcasting compound in the conventional manner. Double relays of this typewith two changeover contacts are preferably used as reversing relay ford.c. motors.

What is claimed is:
 1. Electromagnetic relay with the followingfeatures: a coil body (1) forms a coil tube (11) with two flanges (12,13) and carries a winding (2) on the coil tube (11); a first of the twoflanges (12) forms a switch space (14) with a base side (15) parallel tothe coil axis; within the coil tube (11) there is arranged an axial core(16) which forms a pole face toward the switch space (14) arid isconnected to an L-shaped yoke (20) in the region of the second flange(13); with its free end, the yoke (20) forms, in the region of theswitch space, a bearing edge (21), perpendicular to the base side (15),for a plate-shaped armature (22) which forms a working air gap with thepole face of the core (16); at least one fixed contact support (3)carrying a first fixed contact is secured in the coil body in thevicinity of the moving end of the armature; and a contact spring (23;33) formed from flat strip material is connected to the armature (22),carries a moving contact (25) at one free end (23 a) in the region ofthe moving end of the armature and is connected to a contact springconnecting pin (5) of the relay via a connecting portion (23 c; 33 c),characterised in that the contact spring connecting pin (5) and the atleast one fixed contact support (3, 4) consist of drawn or rolled wireand are embedded in the coil body (1).
 2. Relay according to claim 1,characterised in that a second fixed contact support (4) with a secondfixed contact (7) is embedded in the first coil flange (12) in such away that the moving contact (25) can be switched between the two fixedcontacts (6, 7).
 3. Relay according to claim 2, characterised in thatthe fixed contacts (6, 7) in the form of portions of contact strip arewelded or hard soldered onto the contact supports (3, 4).
 4. Relayaccording to claim 1, characterised in that the contact springconnecting pin (5) is embedded in the first coil flange (12) and in thatthe connecting portion (23 c; 33 c) of the contact spring (23; 33) isfastened directly on a portion of the connecting pin (5) extendingparallel to the bearing edge (21).
 5. Relay according to claim 1,characterised in that the contact spring connecting pin (5) and thefixed contact support (3, 4) consist of square wire or round wire. 6.Relay according to claim 1, characterised in that the core (16) forms apole plate (17) which is configured eccentrically toward the armature.7. Relay according to claim 1, characterised in that the core (16) isembedded in the coil body (1).
 8. Relay according to claim 1,characterised in that the core (16) is plugged into the coil tube and isfixed by means of embossed studs (16 a).
 9. Relay according to claim 1,characterised in that the contact spring (23) is fastened on the yoke(20) by a fastening portion (23 b) and in that a connecting portion (22c) folded over the fastening portion (22 b) is guided to the connectingpin (5).
 10. Relay according to claim 9, characterised in that thefastening portion (23 b) is fastened on the yoke (20) by at least onerivet (26) or welded spot and in that the connecting portion (23 c) hasa recess (27) in the region of each rivet (26) or welded spot.
 11. Relayaccording to claim 1, characterised in that the contact spring (33)rests on the yoke (20) by a bearing portion (33 b) and is connected tothe connecting pin (5) via a connecting portion (33 c) which is cut awayin the region of the armature mounting.
 12. Relay according to claim 1,characterised in that it comprises a housing cap (29) surrounding thecoil flanges (12, 13) and in that the space below the winding is coveredby a base plate (30) arranged between the two flanges (12, 13) and issealed by a casting compound.
 13. Relay according to claim 12,characterised in that the base plate (30) is connected integrally to thehousing cap (29) by a film hinge (31).
 14. Arrangement of at least tworelays according to claim 1, characterised in that the relays arearranged with their coil axes in parallel side by side in a common cap(35), the space beneath the windings being covered by a common baseplate (36).